Saturday, November 13, 2010

Properties in C#

Today my friend asked me a question for which i provided a solution using properties of the class. but then he asked me what are these properties, why to use them and how to Implement them To answer these questions

Definition:Properties are named members of classes, structs, and interfaces. They provide a flexible mechanism to read, write, or compute the values of private fields through accessors. or we can say Properties equip a class with a public way to expose its private members or to get and set values for those private members, while hiding implementation or verification code.A property has two accessors

Get

Set

The get keywordwith the help of this keyword we can define an accessor method for a property or an indexer which retrieves the value of the property or the indexer element.The Set KeywordWith the help of this keyword we can define which accessor is used to assign a new value to the property or indexer.The value keyword is used to define the value being assigned by the set accessor. Properties which do not implement a set accessor are termed as read only Properties.

Let’s take the first example to demonstrate how to declare and use read/write properties.

Example 1This sample shows a Car class that has two properties: Name (string) and Model (int). Both properties have read/write attributes.//car.cs

Notice the way that the properties are declared, for example, consider the Name property:

publicstring Name

{

get

{

return CarName;

}

set

{

CarName = value;

}

}

After declaring the property Set and Get methods are contained inside the declaration. We can control a property is read/write, read-only, or write-only by controlling Get or Set methods. If we only include Get Method the property will be read only if only set method is used the property will be write only (Although very less scenarios I have seen this), and as in our example if both Get and Set are used that means property is read/write.

Once the properties are created or declared, they can be used as if they are the members of that class. The following statementssows both getting and setting the value of a property

mycar.Name = "Maurti";

mycar.ModelNo = 1;

If you have noticed that in a property’s Set method a special value variable is available which we have not declared anywhere. This variable contains the value that the user has specified, for example:

CarName = value;

You can see that these properties are used as other variables only see how we have incremented the ModelNo property

mycar.ModelNo += 1;

The ToString() method is overridden in this example:

publicoverridestring ToString()

{

return"Name = " + Name + ", ModelNo = " + ModelNo;

}

Check that I have not used the ToString() explicitly. It is invoked by default by the WriteLine calls.